Neisseria gonorrhoeae lectin useful as a vaccine and diagnostic marker and means for producing this lectin

Abstract

A bacterial lectin isolatable from Neisseria gonorrhoeae is disclosed. This lectin binds to gonococcal carbohydrates such as gangliotetraosylceramide, has a relative molecular weight of about 22,400 daltons, and an isolectric pH value in the range of about 6.1 to about 6.4. The disclosed lectin is useful as a constituent of a vaccine against gonorrhea and as a diagnostic means for gonorrhea. A method for isolating this lectin is also disclosed, as well as means for producing it.

We claim: 
     
       1. An isolated bacterial lectin, obtainable from gonococci, having a relative molecular weight of about 22,400 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and an isolectric pH value in the range of about 6.1 to about 6.4; said lectin having the ability to bind specifically gangliotetraosylceramide. 
     
     
       2. The bacterial lectin of claim 1 in the form of a pharmaceutically acceptable salt. 
     
     
       3. An inoculum which comprises the isolated bacterial lectin of claim 1 together with a pharmaceutically acceptable carrier therefor. 
     
     
       4. The inoculum in accordance with claim 3 and in unit dose form wherein the lectin is present in an amount of about 10 micrograms to about 500 milligrams. 
     
     
       5. The inoculum in accordance with claim 3 and in unit dose form wherein the lectin is present in an amount of about 100 micrograms to about 500 milligrams. 
     
     
       6. A method of immunizing a human against a gonococcal infection which comprises administering to the human an effective amount of the lectin defined in claim 1 in a pharmaceutically acceptable carrier. 
     
     
       7. The method in accordance with claim 6 wherein about 100 micrograms to about 100 milligrams of the lectin are administered to the human. 
     
     
       8. A method for determining the presence of lectin GCL-1 in a human's body sample comprising the steps of (a) obtaining a body sample from the human;   (b) combining the obtained body sample with antibodies to GCL-1 so as to form an immunoreaction admixture;   (c) maintaining the formed immunoreaction mixture at biological assay conditions for a time period sufficient for the anti-GCL-1 antibodies to bind to any GCL-1 present in said body sample, thereby forming an immunoreactant; and   (d) assaying the maintained admixture for the presence of the immunoreactant.   
     
     
       9. A method for determining the presence of anti-GCL-1 antibodies in a human's body sample comprising the steps of (a) obtaining a body sample from the human;   (b) combining the obtained body sample with an aliquot of the isolated bacterial lectin defined in claim 1 so as to form an immunoreaction admixture;   (c) maintaining the formed admixture at biological assay conditions for a time period sufficient for the isolated bacterial lectin to bind to anti-GCL-1 antibodies present in said body sample, thereby forming an immunoreactant; and   (d) assaying the maintained admixture for the presence of the immunoreactant.   
     
     
       10. A diagnostic system suitable for assaying for Neisseria gonorrhoeae lectin GCL-1, which system comprises, in combination: (a) antibodies to the lectin GCL-1 as defined in claim 1 and (b) indicator means capable of signaling an immunoreaction of said antibodies with said lectin GCL-1. 
     
     
       11. A diagnostic assay system suitable for determining the presence of anti-GCL-1 antibodies in a body sample which system comprises, in combination: (a) the isolated bacterial lectin defined by claim 1 and (b) indicating means capable of signaling an immunoreaction of said antibodies with the lectin. 
     
     
       12. A method of inducing in a warm-blooded animal production of antibodies that immunoreact with lectin GCL-1 as defined by claim 1 which comprises administering to said animal an inoculum containing an effective amount of said lectin in a pharmaceutically acceptable carrier therefor. 
     
     
       13. The method in accordance with claim 12 wherein the inoculum also contains an adjuvant. 
     
     
       14. An isolated DNA fragment capable of expressing the bacterial lectin of claim 1 when contained in an expression vector; said DNA fragment having a coding region for said lectin of no more than about 650 base pairs and a flanking region linked on either side thereof, and said flanking regions together with said coding region containing no more than 10 kb pairs. 
     
     
       15. The isolated DNA fragment in accordance with claim 14 and having no more than about 6 kb pairs. 
     
     
       16. A biological host having a replicable DNA fragment that has a coding region encoding the bacterial lectin of claim 1; said DNA fragment being foreign to said biological host. 
     
     
       17. The biological host in accordance with claim 16 wherein said DNA fragment further includes regulatory signals for expression of said lectin that flank said coding region; said expression regulatory signals being recognized by said biological host but being foreign to said biological host. 
     
     
       18. The biological host in accordance with claim 16 wherein said coding region is the naturally-occurring coding region of Neisseria gonorrhoeae for said lectin. 
     
     
       19. The biological host in accordance with claim 18 wherein said DNA fragment further includes, flanking said naturally-occurring coding region, the naturally occurring Neisseria gonorrhoeae expression regulatory signals for expression of said lectin. 
     
     
       20. A non-chromosomal plasmid vector for propagating DNA in a transcription-translation medium comprising a DNA fragment capable of expressing the bacterial lectin of claim 1 and operatively linked to base pair sequences regulating replication and expression of said DNA fragment, said fragment having a coding region for said lectin of no more than about 650 base pairs and flanking regions linked thereto and together with said coding region containing no more than about 10 kb pairs. 
     
     
       21. A bacterial culture comprising bacteria that contain the plasmid vector of claim 20 and a medium appropriate for the expression of the lectin coded for by the DNA fragment contained therein. 
     
     
       22. The bacterial culture of claim 21 in which said bacterial culture is identified by ATCC Accession Number 67,198. 
     
     
       23. A method of producing a bacterial lectin comprising the steps of: (1) growing a bacterial culture comprising bacteria that contain a non-chromosomal plasmid vector for propagating DNA in a transcription-translation medium which vector contains a DNA fragment capable of expressing the bacterial lectin operatively linked to base pair sequences regulating replication and expression of said DNA fragment under growth conditions appropriate for the bacterial lectin to be expressed in said culture, and   (2) harvesting the expressed bacterial lectin from the bacterial culture.